A technique concerning an exhaust gas purifying apparatus for a hybrid vehicle has been disclosed in the past, for example, by Patent Document 1. In the technique, a catalyst in an exhaust system is preliminarily heated and put into an active state, and an internal combustion engine is then started. Thus the technique intended to reduce exhaust emission.
Furthermore, an automobile exhaust gas purifying system including an HC adsorber catalyst for adsorbing HC and an NOx adsorber catalyst for adsorbing NOx placed at an upstream side of an exhaust gas purifying catalyst has been disclosed, for example, by Patent Document 2. In the conventional purifying system, exhaust gas is adsorbed by the HC adsorber catalyst and the NOx adsorber catalyst before activation of the exhaust gas purifying catalyst. When exhaust gas passes through the HC adsorber catalyst and the like after the activation of the exhaust gas purifying catalyst, HC and NOx adsorbed by the HC adsorber catalyst and the like are desorbed from the adsorber catalysts and purified by the exhaust gas purifying catalyst.
Including the above-mentioned document, the applicant is aware of the following documents as a related art of the present invention.
[Patent Document 1] Japanese Laid-open Patent Application Publication No. Hei 8-338235
[Patent Document 2] Japanese Laid-open Patent Application Publication No. 2005-299631